Former Celtics player Jason Collins is getting a lot of attention for a much-hyped coming out. In the sports world, it doesn’t get bigger than the cover of “Sports Illustrated,” and that’s what Collins got, along with a lengthy, self-penned piece acknowledging his sexuality. Yep, Jason’s gay. But even as Collins supposedly liberates himself, he indulges in stereotypes that one would have thought were left behind decades ago. It’s being called a step forward, and it is, but it’s also a step back.

The big four professional men’s sports — baseball, football, hockey, and basketball — have never featured an openly gay active player, which is what makes Collins’s declaration significant. That announcement was the culmination of efforts in the works for a number of years, led in particular by former Baltimore Raven linebacker Brendon Ayanbadejo — a straight player who has pushed the NFL to open up on gay-related issues. Indeed, Collins’s coming out is expected to be the first of many among professional athletes. Gay men, it turns out, can do sports as well as they can do hair.

That last sentence, by the way, indulges in a stereotype, and a pernicious one at that. And in his SI piece, Collins disturbingly appears to do the same.

“I go against the gay stereotype, which is why I think a lot of players will be shocked: That guy is gay?” writes Collins. Yet it seems clear from his piece that he buys into those same stereotypes, and admires himself for resisting them. He’s gay, you know, but not “gay.” Even after coming to terms with his sexuality, for instance, he says “I still had the same mannerisms.” And, he says, “Note to Shaq: My flopping has nothing to do with being gay.”

And, in particular, Collins latches on to the effeminate man stereotype. Collins has a reputation as an aggressive player. “I take charges and I foul — that’s been my forte.” And why is that? “Am I so physical to prove that being gay doesn’t make you soft? Who knows?”

Collins describes himself as deeply closeted, living a “double life” for some time. In fact, until Collins told him last year, even his twin brother didn’t know. He “never suspected.”

Which makes you wonder. While living his double life, did Collins have to hide a true love for Broadway show tunes? Did he refuse to allow teammates to his home for fear that might see how exceptionally neat it was? Did he have to dress down so fans wouldn’t pick up on his sense of high fashion?

These stereotypes cut both ways, of course. Self-professed straight men who like to cook, don’t follow sports, and are mild-mannered instead of hyper-aggressive are suspected of being closeted. And a guy who’s friends — just friends — with a woman? Well, per “Will and Grace,” you know what that means.

One can discuss forever the nature and truth of stereotypes. At some level, many are accurate. People within a certain subgroup will often develop ways of doing things that are different from others. Through much of history, homosexuality has been outside the norm, with gays often isolated and reviled by conventional society. Some jobs were more open to gays, while some behaviors were used as a way for one gay man to signal to another that they might be members of the same minority. Over time, subcultures developed.

But just as with the stereotype that men of Irish descent (and I count myself one) have a particular inclination to beer, these behaviors are fundamentally choices, not compulsions. There is no genetic link between the Irish and beer, nor is there a genetic link between sexual orientation and the limpness of one’s wrist.

If one looks at people as individuals, rather than groups, you’ll find that — straight or gay — there are a wide variety of behaviors that express themselves as masculine or feminine. One of the triumphs of feminism and gay rights has been to broaden and break down the pigeonholes we have used to define what it means to be a man or a woman. Yet even as the old stereotypes are fading away, Jason Collins seems to hold on to a constrained and outdated sense of what it means to be a man.